Internal combustion engine with blower



July 4, 1939. FAST 2,164,451

INTERNAL COMBUSTION ENGINE WITH BLOWER Filed Sept. 18, 1937 Ihwentor 74 15022 Wzrsi I an ' gZ Gttomegs PatentedJuly 4, 1939 UNITED STATES PATENT OFFICE INTERNAL conrg ugggg ENGINE WITH Marion L. Fast, Detroit, Mich, assignor to Gen? eral Motors Corporation, Detroit, Mich, a corporation oi Delaware Application September 1a, 1937, Serial No. 164,459

7 Claims.

to the inlet 'side of the blower, whereby the actual i vention to a U-type two cycle engine. having a.

work done in driving the blower is proportional to the power developed by the engine.

It is well known that it is very desirable'to preheat the intake air or mixture at lower loads it only in order to approximate the thermal conditions at greater loads and to secure smooth running and eflicient combustion at/the lower loads.

The objectoi' the invention is a means of preheating the air supplied to the engine automatically to a degree varying approximately inversely as the load on the engine, at any given speed.

A more specific object of the invention is to provide an exhaust heated "hot spot" in the bypass passage of a bypass controlled blower.

The above and other objects of the invention will be apparent as the description proceeds.

The drawing shows the application of the inpositive displacement blower driven by the engine at a fixed speed ratio. In the drawing Figt 1 is a sectional elevation of the engine through a pair of cylinder barrels united by a a the engine inlet port 4 by a pipe 12, which has acommon combustion chamber and through the blower and parts according to the invention. Fig. 2 is a section on line 2-4 of Fig. 1.. a. Fig. 3 is a rear elevation 01' a part of Fig. 1. The engine includes a pair of cylinder barrels I and 2, having a common combustion chamber 3. The cylinder barrel I is provided with an inlet port 4, and-the cylinder barrel 2 is provided with an exhaust port 5. The portal and 5 are controlled respectively by the pistons 6 and 1.

Driven from the engine at a fixed speed ratio is the blower 8 having three lobed rotors 9 and II. The inlet H to the blower may be connected to a carburetor (not shown).

The outlet side of the blower is connected to "branch II opening into a passage I! connected tothe inlet side of the blower and constituting a bypass from the outlet to the inlet side of the blower.

Within the pipe II, at a point beyond the branch l3 and closer to the engine, isthe engine butterfly throttle valve I5.

6 IWithin the branch II is a bypass throttle valve The throttle valves i5 and i6 are interconnected in such a way that as one is closed the other is opened, and vice versa. As shown, the operating levers l1 and ll of the throttle valves l5 and i6, respectively, are interconnected by the link I.

A spring loaded valve II is provided at the outlet of the branch I! to ensure that, irrespective of the position of the throttle valves i5 and it, no air or mixture is bypassed until the blower outlet pressure exceeds a certain minimum, determined by the closing pressure of the spring II on the valve 20.

The valve 20 is mushroom shaped, and slides on a guide stem 22 fixed in the cover flange 23 on the outer wall of the passage II, at a point opposite the branch II. The spring 2| has a seating 24 slidable on the boss 25 of the cover flange and provided with an adjustable abutment consisting of a screw 26 with a loclmut 21, through which the pressure of spring 2|, and hence the opening pressure of the valve 20, may be varied.

The exhaust port 5 is connected to an exhaust manifold 3.. A pipe it carries hot exhaust gases from the manifold 30 to a jacket 32 around the branch i3, and thence through the pipe 33 to atmosphere or an exhaust silencer (not shown). It will be seen, that the air or mixture which is recirculated through theblower when the bypass throttle is open, isheated as it passes the exhaust heated "hot spot"; that the quantity recirculated and. heated at any given speed, (provided the blower pressure is suiiicient to open the valve 20), is a maximum at low load when the engine throttle valve I5 is closed and the bypass throttle valve i6 is open, and is a minimum at full load when the engine throttle valve I5 is open and the bypass throttle valve I8 is closed.

While the heating jacket 32 has been shown as applied to that part oi" the bypass constituted by the branch i3, it will be appreciated that the invention is not restricted to such a placement of the heating jacket and that this may be applied to the walls of the bypass in any convenient place where it will heat the air recirculated therethrough as distinct from the air initially entering the blower inlet ii. It will also be appreciated that while the use of the valves l5, l6 and 20 is peculiar to the particular embodiment illustrated, the invention is not restricted to structures in which all or any of these valves are used, but is quite generally applicable to any engine and blower combination in which at part load, a part of the blower output is recirculated through the blower.

I claim:

1. In an internal combustion engine, in combination, a blower for supplying air under pressure to the engine, a bypass from the outlet to the inlet side of the blower, valve means for varying the efiective output oi the blower and the amount of air supplied to the engine by controlling the quantity of air returned through the bypass and re-clrculated through the blower, the quantity of air supplied to the engine being reduced as the quantity of air re-circulated through.

the blower is increased and vice versa, and a hot spot in the bypass whereby the air delivered under pressure from the blower to the engine is preheated to an extent increasing as the quantity of air re-circulated through the blower is increased and the quantity of air supplied to the engine is reduced.

' 2. The combination according 'to claim 1, in which the hot spot is provided by a jacket for the blower bypasaheated by the engine exhaust.

3. The combination according to claim 1, in which the blower is a positive displacement blower driven from the engine.

4. The combination according to claim 1, in

which the valve means includes an engine throttle valve between the blower and the engine, and a bypass throttle valve in the bypass which is connected to the outlet side of the blower between the blower and the engine throttle valve, said throttle valves being interconnected in such a way that as one is closed the other is opened and vice versa.

5. The combination according to claim 1, in which there is a spring loaded valve in the bypass, said valve and its spring being such that no air is bypassed until the blower outlet pressure exceeds a certain minimum determined by the closing pressure of the spring.

6. The combination according to claim 1, in

which a spring loaded valve in the bypass preto the inlet side of the blower, a bypass throttle valve in the bypass, said throttle valves being interconnected in such a way that as one is'closed the other is opened and vice versa, a spring loaded 

